Structure for attaching spring

ABSTRACT

In order to adjust a reaction force of a frame-like spring, the invention provides an attachment structure of a reaction force frame element, which is frame-like spring, having an upper end, which is one end, connected to an upper frame element, which is first attaching object, and a lower end, which is the other end, connected to a lower frame element, which is second attaching object, wherein the upper end is attached to the upper frame element through an upper attaching portion, which is first attaching portion, and the lower end is attached to the lower frame element through a lower attaching portion, which is second attaching portion, and, the lower attaching portion is configured to change a relative angle formed by the reaction force frame element and a downward face, which is attaching face, of the lower frame element.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a structure for attaching a springwhich is entirely formed in a frame, having one end connected to a firstattaching object and other end connected to a second attaching object,respectively.

2. Description of the Related Art

Conventionally, as a method to attach a spring which can accumulatereaction forces due to an elastic deformation so as to be able to adjustthe reaction force, for example, an aspect of fixing one end of acompression coil spring and attaching other end of the compression coilspring in a longitudinal direction movably is considered (for example,please refer to a Japanese Patent Application Laid-Open No. 2003-265256(particularly, refer to FIG. 11)).

Thus, there are various springs other than the compression coil springand among them, there is a spring, which is formed in an elongated shapeextending in a direction, is curved in a direction vertical to thelongitudinal direction, and can accumulate the reaction forces. Anobject of the present invention is to provide means for adjusting thereaction force in such a spring.

SUMMARY OF THE INVENTION

Namely, a structure for attaching spring according to the presentinvention is an attaching structure of spring having one end connectedto a first attaching object and other end connected to a secondattaching object, respectively, and being arranged to these attachingobjects in parallel, wherein the one end is attached to the firstattaching object via a first attaching portion and the other end isattached to the second attaching object via a second attaching portion;and at least one of the first attaching portion and the second attachingportion is formed so as to be able to change a relative angle betweenthe spring and the attaching faces of the first attaching object or thesecond attaching object.

According to such a structure, when the elastic force acting from thespring on the attaching object is made smaller, for example, due to anaging phenomena of the spring, by changing the relative angle into theside where the reaction forces accumulated in the spring is made largerto keep the elastic force or by changing the relative angle when a userfeels that the elastic force received by the backrest from the spring istoo strong or too weak, it is possible to adjust the reaction forcesaccumulated in the spring, namely, the elastic force acting on thebackrest.

As an aspect capable of specifically realizing such a structure, theconstitution that the second attaching portion comprises a shaft memberfor pivotally fitting the spring to the second attaching object, and anadjusting member, which is disposed at a position displaced into theopposite side of the side directed from the shaft member to the firstattaching object, for pressing the second attaching object or the springmay be available.

As a constitution capable of easily realizing the constitution describedin the former clause, the constitution that the adjusting member is amale screw member, and an abutting position with the first attachingobject, the second attaching object, or the spring is changed byscrewing this male screw member backward and forward with respect to afemale screw portion which is disposed penetrating through the firstattaching object or the second attaching object may be considered.Employing such a constitution, since a head portion of the male screwwhich is the adjusting member is exposed on the surface of the oppositeside of the second attaching object, it is possible to adjust theabutting position between the adjusting member and the second attachingobject very easily.

As a constitution capable of easily obtaining the advantages asdescribed above, the constitution that the first attaching object is anupper frame element to form an upper portion of a backrest of a chair,and the second attaching object is a lower frame element to form a lowerportion of the backrest of the chair may be considered. According tosuch a constitution, it is possible to incline the upper frame elementwith respect to the lower frame element and acting the reaction force onthe upper frame element in association with tilt, and further, thereaction force given by the frame-like spring can be adjusted.

As other constitution preferably capable of obtaining theabove-described advantages, the constitution that the first attachingobject is a base to support a seat of a chair and a backrest thereof,and the second attaching object is a back frame to form at least oneportion of the backrest of the chair may be considered. According tosuch a constitution, acting the reaction force on the back frame inaccordance with the rocking operation of the backrest, the rockingreaction force given by the frame-like spring can be further adjusted.

In addition, according to a constitution that the springs are arrangedseparated at a rear face of a backrest of a chair, and the spring hasthe same shape as a back frame, an upper frame element, or a lower frameelement, it is possible to obtain the appearance such that the springseems a portion of the backrest, and the appearance of the chair usingsuch a spring can be arranged.

Employing the attaching structure of the spring according to the presentinvention, when the elastic force acting from the spring on theattaching object is made smaller, for example, due to the agingphenomena of the spring, by changing the relative angle into the sidewhere the reaction forces accumulated in the spring is made larger tokeep the elastic force or by changing the relative angle when a userfeels that the elastic force received by the back from the spring is toostrong or too weak, it is possible to adjust the reaction forcesaccumulated in the spring, namely, the elastic force acting on thebackrest.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view showing a chair of an embodiment accordingto the present invention as seen from the front side thereof;

FIG. 2 is a perspective view showing the chair according to theembodiment as seen from the back side thereof;

FIG. 3 is a side view of the chair according to the embodiment;

FIG. 4 is a rear view of the chair according to the embodiment;

FIG. 5 is a plan view of the chair according to the embodiment;

FIG. 6 is a side view showing the synchronous rocking operation of thechair according to the embodiment;

FIG. 7 is a side view showing the state that an upper frame element onthe chair according to the embodiment is displaced backward;

FIG. 8 is a perspective view showing the deformation operation of abackrest face of the chair according to the embodiment;

FIG. 9 is a plan view showing the deformation operation of a backrestface of the chair according to the embodiment;

FIG. 10 is a side view enlarging the substantial portions of the chairaccording to the embodiment;

FIG. 11 is an exploded perspective view of the substantial portions ofthe chair according to the embodiment;

FIG. 12 is a side view enlarging the substantial portions of the chairaccording to other embodiment of the present invention;

FIG. 13 is a side view of the chair according to other embodiment of thepresent invention;

FIG. 14 is a side view enlarging the substantial portions of the chairaccording to other embodiment of the present invention; and

FIG. 15 is a side view of the chair according to other embodiment of thepresent invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

An embodiment of the present invention will be described below withreference to the drawings.

As shown in FIGS. 1 to 5, the chair according to the present embodimentis provided with a leg 4, a base 2 supported by the leg 4, a seat 3arranged on the base 2, and a backrest 1 pivotally fitted on the base 2via a horizontal support shaft 16, and this chair can carry out thesynchronous rocking operation that the seat 3 and the backrest 1 areinclined in conjunction with each other.

Describing in detail, leg 4 is provided with a leg wing 41 mounting aplurality of casters thereon and a leg support pillar 42 risingapproximately vertically from the center of the leg wing 41 so as to beable to move up and down the leg support pillar 42 due to expansion andcontraction of a gas spring (not illustrated) installed between the legwing 41 and the leg support pillar 42.

The base 2 is fixed to the upper end of the leg support pillar 42, andit is possible to adjust the height positions of the seat 3 and thebackrest 1 through the moving up and down operation of the leg supportpillar 42. The base 2 incorporates an elastic urging mechanism (notillustrated) to urge the backrest 1 turning around the horizontalsupport shaft 16 forward and a fixing mechanism (not illustrated) to fixthe rocking angle of the backrest 1 or the like. The elastic urgingmechanism may elastically urge a back frame 11 by mounting a coil springand a gas spring. It is assumed that the fixing mechanism may fix arocking angle, for example, by selectively engaging a nail to any ofplural steps of recesses disposed to the side of the back frame 11;however, in the case of using the gas spring in a push lock system forthe elastic urging mechanism, an aspect to prohibit the expansion andcontraction operation of the gas spring by driving a bulb of the gasspring may be possible.

The seat 3 is configured so as to hold a cushion body 32 constituting aseat face on a seat receiver 31. The cushion body 32 is made as a doublelayered structure superimposing a urethane cushion material on a doubleraschel mesh, for example, made of a synthetic fiber, the mesh at thelower layer secures an appropriate elasticity while absorbing the shock,and the urethane cushion material of the upper layer keeps a stabilityof a posture. The front end of the seat 3 is supported by the base 2 soas to slidably move in a back and front direction for the base 2, andthe rear end of the seat 3 is attached to the lower frame portion 13 ofthe back frame 11 via a hinge (not illustrated).

The backrest 1 is made by attaching an upholstery member 12 configuringthe backrest face S on the front face of the back frame 11. The backframe 11 is provided with the lower frame portion 13 which is turnablyconnected around the horizontal support shaft 16 with respect to thebase 2, the upper frame portion 14 which is connected to the upper endof the lower frame portion 13 via the hinge 17, and the reaction forceframe portion 15 which is a spring member formed in a frame shape tosupport this upper frame portion 14 from behind.

The lower frame portion 13 is made by mutually connecting the right andleft upper elements 131 a and 131 b separately arranged in a widthdirection by a rigid lateral bridging material 132. The lower frameelements 131 a, 131 b, and the rigid lateral bridging material 132 arerigid bodies, for example, made of a metal. The lower frame elements 131a and 131 b are elongated from the front end where the horizontalsupport shaft 16 is located to the rear portion and curved upward at therear end to be made into approximately an L-shape as seen from the side.

The upper frame portion 14 is made by mutually connecting the right andleft upper frame elements 141 a and 141 b separately arranged in a widthdirection by an elastic lateral bridging material 142. The upper frameelements 141 a and 141 b are rigid bodies, for example, made of a metal;however, the elastic lateral bridging material 142 is an elastic body,for example, made of a resin. The upper frame elements 141 a and 141 bare slowly curved from the lower end where the hinge 17 is located andis elongated upward while getting dented backward in some degree so asto be made into an arch swelled forward again in the vicinity of itsupper end as seen from the side.

The reaction force frame portion 15 is made of reaction force frameelements 151 a and 151 b which are frame-like springs of the same numberto support each of the upper frame elements 141 a and 141 b.

Thus, according to the present invention, the reaction force frameelements 151 a and 151 b have their one ends and other ends connected tothe lower frame elements 131 a and 131 b which are the first members,and the upper frame elements 141 a and 141 b which are the secondmembers, respectively. The reaction force frame elements 151 a and 151 bcan accumulate the reaction forces due to the elastic deformation, andthese reaction force frame elements 151 a and 151 b are formed in aframe shape which is elongated along the upper frame elements 141 a and141 b and the lower frame elements 131 a and 131 b.

Specifically, lower ends 152 a and 152 b, which are one ends of thereaction force frame elements 151 a and 151 b, are linked with thedownward faces of the lower attaching portions 133 a and 133 b,respectively; and upper ends 153 a and 153 b are linked with the rearfaces of the upper frame elements 141 a and 141 b, respectively.However, other ends of the reaction force frame elements 151 a and 151 bare not prevented from being fixed on the seat 3 and the base 2supporting the backrest 1. It is assumed that the reaction force frameelements 151 a and 151 b are made of an elastic body made of a resin ofthe same quality, for example, as the elastic lateral bridging material132. According to the present embodiment, the reaction force frameelements 151 a and 151 b are frame-like springs made of a resin, whichare elongated along the lower frame elements 131 a and 131 b and theupper frame elements 141 a and 141 b so as to be made into approximatelya L-shape as seen from the side. These reaction force frame elements 151a and 151 b are molded in such a manner that the width measurements arethe same or slightly smaller than those of the frame elements 131 a, 131b, 141 a, and 141 b and the back and forth or the upper and lowerthicknesses thereof are thinner than those of the frame elements 131 a,131 b, 141 a, and 141 b (in addition, they are becoming graduallythinner as being far from the end to be connected to the frame elements131 a, 131 b, 141 a, and 141 b). Thereby, the appearance such that thereaction force frame elements 151 a and 151 b seem a portion of the backframe 11 branched from the frame elements 131 a, 131 b, 141 a, and 141 bis formed.

In the periphery of the hinge 17 to pivotally fit the lower frameelements 131 a and 131 b and the upper frame elements 141 a and 141 bwith each other, specifically, from the rear ends of the lower frameelements 131 a and 131 b to the vicinity of the upper ends thereof andin the range in the vicinity of the lower ends of the upper frameelements 141 a and 141 b, a curved shape that the front face of theframe is swelled forward as seen from the side is formed. As describedabove, also in the vicinity of the upper ends of the upper frameelements 141 a and 141 b, a curved shape that the front face of theframe is swelled forward as seen from the side is formed. Thus, theupholstery member 12 is tensed so as to be bridged to theabove-described region formed in the curved shape of the lower frameelements 131 a and 131 b and the upper frame elements 141 a and 141 b.

The upholstery member 12 is mainly made by a stretch upholstery fabric.The upholstery fabric is made by weaving an elastic thread such as anelastomer thread or the like in a double raschel mesh, for example, of asynthetic resin and this upholstery fabric has both of strength and acushion capability. The upholstery fabric has different appearances(color, pattern, and brilliance or the like). The upper side and rightand left sides of the upholstery fabric are kept by a backup material(not illustrated) formed in a three-way frame or a four-way frame asseen from the front. The backup material is a thin plate made of, forexample, a resin, and particularly, this backup material prevents theright and left sides of the upholstery fabric from being flexed insideto keep the upholstery fabric into the tensed state. The upper end ofthe upholstery member 12 is installed in the right and left upper frameelements 141 a and 141 b to be supported, and the lower ends areinstalled in the right and left lower frame elements 131 a and 131 b tobe supported. In this case, the backup material practices the action ofa plate spring and presses the upholstery fabric to be evaginated.

Further, it is also possible to bridge a lumber support belt 18 at theheight position corresponding to the waist portion of a person who isseated on the chair at the back of the upholstery member 12. Even whenthe person who is seated on the chair leans against the backrest face S,the region where the lumber support belt 18 is bridged does not sinkbackward more than a depth corresponding to the length of the lumbersupport belt 18.

The chair according to the present embodiment can perform thesynchronous rocking operation that the seat 3 and the backrest 1 areinclined in conjunction with each other. As shown in FIG. 6, accordingto the synchronous rocking operation, the backrest 1 is inclinedbackward and forward by entirely turning the back frame 11 around thehorizontal support shaft 16. At the same time, the rear end of the seat3 is swung upward and downward in conjunction with the back frame 11 andthe front end of the seat 3 is slid backward and forward.

On that basis, in the chair according to the present embodiment, theoperation is possible to displace only the left half of the upperportion of the backrest face S backward or only the right half thereofbackward following the movement that the person who is seated on thechair turns his or her head to look back in the seat, extends his or herarm, and twists his or her body. In the upper frame portion 14supporting the upper portion of the backrest face S moves backward andforward, the upper frame elements 141 a and 141 b move independentlyeach other, which are paired in right and left. In other words, theupper frame element 141 a at the left side is connected to the lowerframe element 131 a at the left side via the hinge 17, and the upperframe element 141 b at the right side is connected to the lower frameelement 131 b at the right side via the hinge 17. These upper frameelements 141 a and 141 b can turn individually.

As shown in FIG. 7, when the upper frame elements 141 a and 141 b areinclined backward around the hinge 17, the area where the upholsterymember 12 contacts the region formed in the curved shapes of the lowerframe elements 131 a and 131 b and the upper frame elements 141 a and141 b gradually increased, and further, the upholstery fabric extendsupward and downward while increasing a tension. In addition, thereaction force frame elements 151 a and 151 b are deformed to extendangles and accumulate the reaction forces therein. Then, the reactionforce frame elements 151 a and 151 b elastically urge the upper elements141 a and 141 b to the original positions, namely, forward.

Then, if any one of the upper frame elements 141 a and 141 b relativelydisplaced in a back and front direction for other one of the upper frameelements 141 a and 141 b, as shown in FIG. 8 and FIG. 9, it is possibleto change the shape of the backrest face S three-dimensionally. In thisoperation, the lower frame portion 13 is not necessarily driven. Inaddition, since the lower frame elements 131 a and 131 b to be pairedleft and right are rigidly connected via the rigid lateral bridgingmaterial 132, these lower frame elements 131 a and 131 b constantly makea movement in a unified manner. Therefore, the lower portion of thebackrest face S, namely, the portion backward from the waist portion ofthe person who is seated on the chair constantly keeps a predeterminedshape.

If one of the upper frame elements 141 a and 141 b relatively movesbackward and forward to other one of them in accordance with themovement of the person who is seated on the chair, a distance betweenright and left upper frame elements 141 a and 141 b increased. In thiscase, in order to correspond to increase of the distance between theseframe elements 141 a and 141 b, the elastic lateral bridging material142 is elastically deformed. The elastic lateral bridging material 142of the present embodiment connects the upper ends of the frame elements141 a and 141 b with each other to be assembled to make the curved shapegetting dented backward as seen from the flat face. The back and frontthickness of the elastic lateral bridging material 142 is graduallythinner toward the center in the width direction thereof from theopposite ends thereof connected to the upper frame elements 141 a and141 b, so that the center portion is comparatively deformable than theopposite ends. This structure serves to prevent the load from gettingcentered on the place where the upper frame elements 141 a and 141 b areconnected to the elastic lateral bridging material 142. When one of theupper frame elements 141 a and 141 b relatively moved backward andforward against other one of them, the elastic lateral bridging material142 is deformed so as to decrease a curvature factor and extends thedistance between the opposite ends.

In addition, the load of the person who is seated on the chair given tothe backrest S may act on the upper frame elements 141 a and 141 b viathe upholstery member 12 and may give the load on the hinge 17 so as toincline the upper frame elements 141 a and 141 b inward. In order toreduce such a load, the elastic lateral bridging material 142 isassembled so that it exercises the initial elasticity so as to separatethe upper frame elements 141 a and 141 b in a width direction.

It is also possible to incline both of the upper frame elements 141 aand 141 b via the upholstery member 12. In this case, for example,stretch to largely through his or her back becomes possible.

Thus, the present embodiment may provide a structure for attachingspring having one end connected to a first attaching object and otherend connected to a second attaching object, respectively, and arrangedthese attaching objects in parallel, wherein one end is attached to thefirst attaching object via a first attaching portion and other end isattached to the second attaching object via a second attaching portion;and at least one of the first attaching portion and the second attachingportion is formed so as to be able to change a relative angle betweenthe spring and the attaching faces of the first attaching object or thesecond attaching object.

Specifically, as shown in FIGS. 1 to 9, and as shown in FIG. 10 which isa side view enlarging the substantial portions and FIG. 11 which is theexploded perspective view of the substantial portions, respectively, thefirst attaching objects are the upper frame elements 141 a and 141 b,the second attaching objects are the lower frame elements 131 a and 131b, and the springs are the reaction force frame elements 151 a and 151b. In addition, the first attaching portions are the upper attachingportions 143 a and 143 b, and the second attaching portions are thelower attaching portions 133 a and 133 b, respectively. Then, theselower attaching portions 133 a and 133 b are provided with shaft members1331 a and 1331 b for pivotally fitting the reaction force frameelements 151 a and 151 b and the lower frame elements 131 a and 131 b,and adjusting members 1332 a and 1332 b disposed at a position displacedinto the opposite side of the side directed from the shaft members 1331a and 1331 b to the upper frame elements 141 a and 141 b for pressingthe reaction force frame elements 151 a and 151 b. In addition, theadjusting members 1332 a and 1332 b are male screw members according tothe present embodiment, and by screwing backward and forward theseadjusting members 1332 a and 1332 b with respect to female screwportions 131 ay and 131 by formed protruding through the lower frameelements 131 a and 131 b, the abutting positions with the reaction forceframe elements 151 a and 151 b are changed. Further, the reaction forceframe elements 151 a and 151 b are formed in the shapes similar to thoseof the upper frame elements 141 a and 141 b and the lower frame elements131 a and 131 b to be arranged at the rear face side of the backrest 1,for more detail, they are arranged separated into the rear face sides ofthe upper elements 141 a and 141 b and the rear face sides of the lowerframe elements 131 a and 131 b.

More specifically, the lower ends 152 a and 152 b of the reaction forceframe elements 151 a and 151 b are provided with projections 154 a and154 b projecting toward the lower frame elements 131 a and 131 b. On theother hand, on the attaching faces of the lower frame elements 131 a and131 b, namely, on the downward faces 131 a 1 and 131 b 1 , attachingconcave portions 131 ax and 13 bx capable of accommodating theseprojections 154 a and 154 b, respectively, are provided. Further, byinserting these shaft members 1331 a and 1331 b in shaft inserting holes131 az and 131 bz formed on these lower frame elements and shaftinserting holes 154 ax and 154 bx formed on the reaction force frameelements with the these projections 154 a and 154 b accommodated inthese attaching concave portions 131 ax and 131 bx, the reaction forceframe elements 151 a and 151 b are pivotally fitted to the lower frameelements 131 a and 131 b, respectively.

On the other hand, the female screw portions 131 ay and 131 by aredisposed at the opposite side of the upper frame elements 141 a and 141b from the attaching concave portions 131 ax and 131 bx, namely, theposition which is displaced to the lower front side.

In other words, in the chair C according to the present embodiment, ifthe adjusting members 1332 a and 1332 b are moved downward with respectto the female screw portions 131 ay and 131 by, the lower ends of theseadjusting members 1332 a and 1332 b may press the lower ends of thereaction frame elements 151 a and 151 b. Then, the lower ends 152 a and152 b of the reaction force frame elements 151 a and 151 b may turnaround the shaft members 1331 a and 1331 b, and a relative angle betweenthe reaction force frame elements 151 a and 151 b and the downward faces131 a 1 and 131 b 1 of the lower frame elements 131 a and 131 b ischanged. On the other hand, if the adjusting members 1332 a and 1332 bare moved upward, the reaction force frame elements 151 a and 151 b areelastically deformed, and the lower ends of the reaction force frameelements 151 a and 151 b move upward while keeping the state that theyabut against the adjusting members 1332 a and 1332 b. Also in this case,the lower ends of the reaction force frame elements 151 a and 151 b mayturn around the shaft members 1331 a and 1331 b, so that the relativeangle between these reaction force frame elements 151 a and 151 b andthe downward faces 131 a 1 and 131 b 1 of the lower frame elements 131 aand 131 b is changed. Accordingly, if these adjusting members 1332 a and1332 b are screwed backward and forward with respect to the female screwportions 131 ay and 131 by formed on the lower frame element 131 a and131 b penetrating therethrough, the postures of the reaction force frameelements 151 a and 151 b are changed, and this makes it possible tochange the reaction forces to be accumulated in these reaction forceframe elements 151 a and 151 b.

As described above, according to the present embodiment, it is possibleto realize the following effect since the lower attaching portions 133 aand 133 b as the second attaching portion are configured so as to becapable of changing the relative angle between the reaction force frameelements 151 a and 151 b as the spring and the downward faces 131 a 1and 131 b 1 as the attaching faces of the lower frame elements 131 a and131 b as the second attaching object. In other words, when the elasticforce acting on the upper frame elements 141 a and 141 b is made smallerdue to an aging phenomena of the reaction force frame elements 151 a and151 b, by changing the relative angle between these reaction force frameelements 151 a and 151 b and the downward faces 131 a 1 and 131 b 1 intothe side where the reaction forces accumulated in the reaction forceframe elements 151 a and 151 b are made larger to keep the elastic forceor by changing the relative angle when a user feels that the elasticforce received by the backrest 1 from the reaction force frame elements151 a and 151 b is too strong or too weak, it is possible to adjust thereaction forces accumulated in the reaction force frame elements 151 aand 151 b, namely, the elastic force acting on the backrest 1.

In addition, since the present embodiment employs the constitution suchthat the lower attaching portions 133 a and 133 b are provided with theshaft members 1331 a and 1331 b for pivotally fitting the reaction forceframe elements 151 a and 151 b to the lower frame elements 131 a and 131b and the adjusting members 1332 a and 1332 b provided at a positiondisplaced into the opposite side from the side directed from the shaftmembers 1331 a and 1331 b toward the upper elements 141 a and 141 b forpressing the lower frame elements 131 a and 131 b, such a reactionadjusting mechanism can be realized with a simple structure.

Further, since the adjusting members 1332 a and 1332 b are male screwmembers, and these adjusting members 1332 a and 1332 b are screwedbackward and forward with respect to the female screw portions 131 ayand 131 by formed on the lower frame element 131 a and 131 b penetratingtherethrough so as to change the abutting position with the lower frameelements 131 a and 131 b, it is possible to easily realize theconstitution described in the former clause. Further, the headportionsof the male screw members as the adjusting members 1332 a and 1332 b areexposed to the surfaces at the opposite sides of the lower frameelements 131 a and 131 b, namely, on the upward face, and this makes itpossible to adjust the abutting position between the adjusting members1332 a and 1332 b and the lower frame elements 131 a and 131 b veryeasily.

Then, the reaction force frame elements 151 a and 151 b are arranged tobe separated on the rear face of the backrest 1, and the reaction forceframe elements 151 a and 151 b have the same shapes as those of theupper frame elements 141 a and 141 b, and the lower frame elements 131 aand 131 b, so that the appearance such that the reaction force frameelements 151 a and 151 b seem a portion of the backrest 1 can be formedso as to straighten the appearance of the chair C.

In addition, the present invention is not limited to the embodimentsdescribed above in detail.

For example, as shown in FIG. 12 which is a side view enlarging thesubstantial portions, according to the above-described embodiments, thefemale screw holes 151 ax and 151 bx are disposed penetrating throughthe reaction frame elements 151 a and 151 b, and an aspect so as to abutthe head portions of the adjusting members 1332 a and 1332 b as the malescrew members against the lower face of these reaction frame elements151 a and 151 b is also possible. According to this aspect, byelastically deforming the reaction force frame elements 151 a and 151 bwhile screwing the adjusting members 1332 a and 1332 b backward andforward with respect to these female screw holes 151 ax and 151 bx andmaintaining the state of abutting the head portions of the adjustingmembers 1332 a and 1332 b against the lower faces of these reactionforce frame elements 151 a and 151 b, the relative angle between thereaction force frame elements 151 a and 151 b and the downward faces 131a 1 and 131 b 1 as the attaching faces of the lower frame element 131 aand 131 b is changed.

Further, as shown in FIG. 13 which is a side view, upper ends A152 a andA 152 b as one ends of reaction force frame elements A151 a and A151 bformed in a frame shape and the lower ends as other ends are connectedto the upper frame elements 141 a and 141 b as the first members and thebase 2 as the second member, respectively, and as shown in FIG. 14,lower attaching portions 21 a and 21 b as the second attaching portionsfor connecting these reaction force frame elements A151 a and A151 b,and the base 2 may be configured in the same way as the second attachingportion in the above-described embodiment. In other words, pivotallyfitting the lower ends of the reaction force frame elements A151 a andA151 b and the base 2 are via shaft members 211 a and 211 b andproviding an adjusting member 212 b at a region displaced from theseshaft members 211 a and 211 b into the opposite sides of the upper frameelements 141 a and 141 b, the relative angle between the reaction forceframe elements 151 a and 151 b and the downward face 2 a as theattaching face of the base 2 may be changed.

In addition, as shown in FIG. 15 which is a side view, the attachingposition of the reaction force frame elements 151 a and 151 b as thespring for the lower frame elements 131 a and 131 b as the secondmembers is configured so as to be capable of being changed between theposition, for example, represented by a solid line in FIG. 15 and theposition, for example, represented by an imaginary line, and theattaching position of the reaction force frame elements 151 a and 151 bfor the upper frame elements 141 a and 141 b as the first member is setat only one place. By changing the attaching position for the lowerframe elements 131 a and 131 b, the reaction force frame elements 151 aand 151 b are elastically deformed, and the relative angle between thesereaction force frame elements 151 a and 151 b at the rising position andthe downward faces 131 a 1 and 131 b 1 as the attaching faces of thelower frame elements 131 a and 131 b is changed so as to enable tochange the reaction force given by these reaction force frame elements151 a and 151 b. Such an aspect may be also possible.

Even if these aspects are employed, since the relative angle between thereaction frame element as the spring and the attaching face can bechanged, the advantages according to the above-described embodiments canbe completely obtained.

Then, the constitution such that, at the first attaching side not thesecond attaching side, in the above-described example, at the upperattaching portion not the side of the lower attaching portion, therelative angle between the above-described reaction frame element andthe rear face as the attaching face of the upper frame element can bechanged may be employed. Further, it is obvious that such a constitutionmay be used for the both of the lower attaching portion and the upperattaching portion.

In addition, the present invention may be used for not only the backrestof the chair but also for the general regions to attach one end to thefirst attaching object via the first attaching portion and attach otherend to the second attaching object via the second attaching portion in astructure for attaching spring which is entirely formed in a frame,having one end connected to a first attaching object and other endconnected to a second attaching object, respectively.

Other than this, various modifications are possible within the rangewithout departing from the scope of the present invention.

1. A structure for attaching spring having one end connected to a firstattaching object and other end connected to a second attaching object,respectively, and being arranged to these attaching objects in parallel,wherein one end is attached to the first attaching object via a firstattaching portion and other end is attached to the second attachingobject via a second attaching portion; and at least one of the firstattaching portion and the second attaching portion is formed so as to beable to change a relative angle between the spring and the attachingfaces of the first attaching object or the second attaching object. 2.The structure for attaching spring according to claim 1, wherein thefirst attaching portion comprises a shaft member for pivotally fittingthe spring to the first attaching object, and an adjusting member, whichis disposed at a position displaced into the opposite side of the sidedirected from the shaft member to the second attaching object, forpressing the first attaching object or the spring.
 3. The structure forattaching spring according to claim 1, wherein the second attachingportion comprises a shaft member for pivotally fitting the spring to thesecond attaching object, and an adjusting member, which is disposed at aposition displaced into the opposite side of the side directed from theshaft member to the first attaching object, for pressing the secondattaching object or the spring.
 4. The structure for attaching springaccording to claim 2, wherein the adjusting member is a male screwmember, and an abutting position with the first attaching object, thesecond attaching object, or the spring is changed by screwing this malescrew member backward and forward with respect to a female screw portionwhich is disposed penetrating through the first attaching object or thesecond attaching object.
 5. The structure for attaching spring accordingto claim 1, wherein the first attaching object is an upper frame elementto form an upper portion of a backrest of a chair, and the secondattaching object is a lower frame element to form a lower portion of thebackrest of the chair.
 6. The structure for attaching spring accordingto claim 1, wherein the first attaching object is a back frame to format least one portion of a backrest of a chair, and the second attachingobject is a base to support a seat of the chair and the backrestthereof.
 7. The structure for attaching spring according to claim 1,wherein the springs are arranged separated at a rear face of a backrestof a chair, and the spring has the same shape as a back frame, an upperframe element, or a lower frame element.
 8. The structure for attachingspring according to claim 3, wherein the adjusting member is a malescrew member, and an abutting position with the first attaching object,the second attaching object, or the spring is changed by screwing thismale screw member backward and forward with respect to a female screwportion which is disposed penetrating through the first attaching objector the second attaching object.
 9. The structure for attaching springaccording to claim 2, wherein the first attaching object is an upperframe element to form an upper portion of a backrest of a chair, and thesecond attaching object is a lower frame element to form a lower portionof the backrest of the chair.
 10. The structure for attaching springaccording to claim 3, wherein the first attaching object is an upperframe element to form an upper portion of a backrest of a chair, and thesecond attaching object is a lower frame element to form a lower portionof the backrest of the chair.
 11. The structure for attaching springaccording to claim 4, wherein the first attaching object is an upperframe element to form an upper portion of a backrest of a chair, and thesecond attaching object is a lower frame element to form a lower portionof the backrest of the chair.
 12. The structure for attaching springaccording to claim 2, wherein the first attaching object is a back frameto form at least one portion of a backrest of a chair, and the secondattaching object is a base to support a seat of the chair and thebackrest thereof.
 13. The structure for attaching spring according toclaim 3, wherein the first attaching object is a back frame to form atleast one portion of a backrest of a chair, and the second attachingobject is a base to support a seat of the chair and the backrestthereof.
 14. The structure for attaching spring according to claim 4,wherein the first attaching object is a back frame to form at least oneportion of a backrest of a chair, and the second attaching object is abase to support a seat of the chair and the backrest thereof.
 15. Thestructure for attaching spring according to claim 2, wherein the springsare arranged separated at a rear face of a backrest of a chair, and thespring has the same shape as a back frame, an upper frame element, or alower frame element.
 16. The structure for attaching spring according toclaim 3, wherein the springs are arranged separated at a rear face of abackrest of a chair, and the spring has the same shape as a back frame,an upper frame element, or a lower frame element.
 17. The structure forattaching spring according to claim 4, wherein the springs are arrangedseparated at a rear face of a backrest of a chair, and the spring hasthe same shape as a back frame, an upper frame element, or a lower frameelement.